They drank beer, then played table tennis in the crew quarters using a new ball Gaines had brought  along. The game being a version of his own devising, its rule-like structures and boundary conditions changing visit by visit, Gaines won. Shortly after that, carbon  dioxide levels were raised sharply all the way across the Tub environment.  Alarms went off. Van Sant had to suit up and go outside – where the ongoing tantrums of probability self-cancel to vacuum – and hit something  twice with a wrench; then they had to dump the greenhouse and start again. By then it began to be time for Gaines to leave.

‘Biology,’ he said with a chuckle. ‘Don’t you just wish you could do without it?’

‘Very funny.’

After his friend had gone, Impasse van Sant sat tiredly in the bottom  half of the eva suit and  told himself: ‘I hate going out there. I can feel that thing looking at me.’ He meant the K-Tract. Gaines felt differently about it, he knew. Like everyone else, Imps had very little idea how he fitted into  his friend’s schemes: but he sometimes thought that Rig visited the Tub because it was the only place he could relax. Rig loved it out in the dark, away from everything human. Van Sant felt less than comfortable with that. Some time ago – too long ago, perhaps – he had become aware of the Tract hanging up there in front of him, year on year like a huge boiling face – stripped, raw, raddled with Bok globules and dust lanes, flattened and stretched laterally by poorly-understood relativistic effects, heaving with emotions you couldn’t recognise.

It made him feel routinely anxious. It made him feel alone. So as soon as he was sure Rig Gaines had gone he opened a spread of communications  channels and whispered into empty space:

‘Hey, babe. Are you out there?’

No answer today.

The assistant booked a ticket to Kunene. Tide-locked with its local sun so that one side froze and the other cooked, this medium-sized venue a few lights into the Bay offered a single habitable time-zone known  as ‘the Magic Hour’. Rare earth  oxides had kick-started Kunene’s first phase of commerce, but it was the Magic Hour’s fixed and subtly graded bands of sunset action that brought in the investment partners: badlands, ghost towns and wreck-littered coastal benches seduced tourist and corporate image-maker alike, confirming  Kunene as the Halo’s primo  location for everything from amateur wedding holography through ‘existence porn’ to the edgiest of brand initiatives.

Everyone who enjoys a sunset wishes it would never end; on Kunene, the brochures promised, you could have that wish.